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Bleaching
Reduction of natural coloring matter to produce white fabric and must be accomplished with a minimum damage of cotton being bleached.
Objectives of Bleaching
- To impart a pure permanent and basic white effect to the fabric.
- To increase the absorbency of the fabric.
- To produce white finishes
- To make textile material suitable for the subsequent process
Bleaching agent and their classification :
The material by which bleaching is done is called bleaching agent.
There are two types of bleaching agent.
- Oxidizing bleaching agent
- Reducing Bleaching agent
- Oxidizing Bleaching agent : the bleaching agent which fulfills bleaching process by producing unsaturated oxygen is called oxidizing Bleaching Agent
- Reducing Bleaching agent: The bleaching agent which fulfills bleaching process by producing other unsaturated elements rather than oxygen is called reducing bleaching agent.
Some example of two types of bleaching agent
Oxidizing Bleaching Agent | Reducing Bleaching Agent |
Hypochlorite (NaOCl) (CaOCl2) | Zinc Dust |
Bleaching Powder | Stannous Chloride (SnCl2) |
Hydrogen Peroxide | Sulfur Di.Oxide (SO2) |
Potassium Dichromate | Ferrous Sulphate (FeSO4) |
Sodium Chloride (NaCl) | Sodium Hydrosulphate (NaHSO4) |
Ozone (O3) | Hydrogen Sulphite H2S |
Potassium Per Manganet K2MnO4 |